Apparatus for coating

ABSTRACT

An apparatus is described for applying coating material in a fluid state to a receptor surface (in the form of a moving web) through a porous member having a large number of fine drillings. The porous member may be a block of epoxy resin and a base plate of a chamber containing the epoxy resin block.

O United States Patent 1191 1111 3,792,682

Phipps 1451 Feb. 19, 1974 [54] APPARATUS FOR COATING 2,349,256 5 1944Evans 118 411 1751 11116111011 Raymond Harold Phipps, Bristol, 2 23332?311332 3222155311111 131:; 1131115 England 2,761,418 9/1956 Russell 1118/410 [731 Assignee The Waxed 1 333???? $1322 $251 113/313 CompanyEngland 3:509:849 5/1970 Blair 6161:: IIII 118 411 x [22] Fil d; M 6,1972 3,589,331 6/1971 Westervelt 118/62 [21] 232,007 FOREIGN PATENTS ORAPPLICATIONS Related U.S. Application Data 447,219 5/1936 Great Britain118/411 [63] Continuation-impart of Ser. No. 873,053, Oct. 31,

1969, abandoned.

Przmary Examiner-John P. McIntosh [30] Foreign Application Priority DataDec. 1, 1968 Great Britain 51829/68 June 16, 1969 Great Britain 30484/69{57] ABSTRACT An apparatus is described for applying coating mate-118/62 8/41 rial in a fluid state to a receptor surface (in the form n cof a moving web) through a porous member having a [58] Field of Search118/410, 411, 415, 401, 62 large number of fine drillings The porousmember may be a block of epoxy resin and a base plate of a [56]References Clted chamber containing the epoxy resin block.

UNITED STATES PATENTS 1,613,521 1/1927 Martin 118/411 X 5 Claims, 4Drawing Figures sum 20F g PATENIEB FEB 1 91974 APPARATUS FOR COATINGThis application is a continuation-in-part of my copending applicationSer. No. 873,053, filed Oct. 31, 1969, now abandoned.

This invention relates to the application of coating materials in afluid state to a receptor surface in the form of a moving web and isconcerned with the method and apparatus of the kind in which fluid isapplied to the surface through a porous member.

According to this invention there is provided an apparatus for applyingcoating material in a fluid state to a receptor surface comprising amember drilled to provide pores of uniform size uniformly distributed inthe member to provide a porous member, and means for dispensing fluidthrough the said member to the receptor surface. Preferably the block isformed in a chamber or recess provided in a coating head which includesa base plate at the bottom of the chamber, and said plate being drilledwith the said block to provide the desired porosity. The block may bemade of metal loaded epoxy resin.

Preferably the moving web is held in contact with the coating head by anair supported membrane.

One form of apparatus for carrying out the invention is illustrated inthe accompanying drawing, wherein:

FIG. 1 is aperspective view of a coating device for applying a coatingto a moving web,

FIG. 2 is an end view of the coating device shown in FIG. 1,

FIG. 3 is a detail view of the porous member shown in FIG. 2, and

FIG. 4 is a perspective view of the device used for air supporting themembrane.

Referring to the drawing and first to FIG. 1. The coating devicecomprises an applicator head generally indicated at 2 which is suspendedby means of arms 4 mounted on brackets 6 of a crossbar 8 of the frame 10of the machine above the surface of a moving web 12 to be coated. Theapplicator head 2 is provided with adjustable air-pressure control means14 for controlling the loading of the head 2 from the regulator 16.Beneath the web 12 is positioned means for maintaining the web 12 inuniform contact with the applicator head 2 comprising an air-supportedmembrane 18 in the form of a belt made for example of fabric reinforcedsilicone rubber 0. l4 thick passing over rollers 20 and 21, the roller21 being the driving roller. The bottom roller 20 is adjustable tocontrol tension. The belt 18 is tendency driven by means of roller 21which is coupled to the main drive of the coating machine through amagnetic particle coupling (not shown) so as to control the drag of thebelt on the supported web. A fourth roller 22 is a roll which can eitherbe kept at chill temperature or heated if required by means of coolingor heating liquid or gas so as to maintain the belt at any temperaturesuitable for the particular coating conditions. The rollers 20 aremounted on a framework 24 attached to the frame 10 of the machine.

Under the upper run of the belt 18 there is provided air supportingmeans 26 for holding the belt 18 in contact with web 12 by which meansthe web 12 is held in contact with the applicator head 2. The airsupporting means 26 takes the form of a box, the details of which aredescribed later with reference to FIGS. 2 and 4.

The applicator head 2 is built to provide an elongate coating chamber 30having three inlets 32 in the top surface. The chamber 30 contains aporous block 34 and a filter 36 is arranged above the block in thechamber 30. The bottom wall of the chamber 30 is formed integrally withthe walls 38 and provides a base plate 40 which is in contact with theweb to be coated. Other features contained in the head 2 are L-shapedheaters 42 for maintaining the coating at the correct temperature and asmoothing bar assembly 44 incorporating two downwardly projectingsmoothing bars 46. The block 34 is made by pouring metal loaded epoxyresin into the chamber 30 where it is cured in situ in the bottomportion of the chamber 30. The base plate 40 and block 34 together formthe porous member which is made by drilling a plurality of holes 48through the plate 40 and the block 34. The diameter of the drilled holesor pores 48 and the distance between said holes and the thickness of theblock are predetermined depending upon the material which is to beapplied to the web so as to provide a calibrated impedance to flow. Forexample a porous member may consist of a plate 40 1/16 inches inthickness and a block 34 of epoxy resin 3/16 inch in thickness. In thiscase holes or pores 48 are drilled to provide rows 1/16 inch apart andthe pores are 0.02 inch in diameter at 1/l6 inch centres apart, thepores of one row being staggered in relation to those of the next row.

FIG. 4 shows in detail the means for air supporting the belt 18. A box50 fixed under the upper run of the belt 18 is divided into compartments51 and a top plate 52 is bolted to the body of the box. The top plate 52is perforated in zones. Zone a provides a row ofjets under a roller 19maintaining the web 12 in contact with the belt 18 before the web 12reaches the coating head 2. Zone 17 provides a double row of jets underthe coating head 2 and zone 0 provides a double row ofjets under the twosmoothing bars 46. Conveniently the holes are of diameter l/32 at 3/32inch centres. Air is supplied under pressure to the box the compartments51 being individually fed through apertures 53 with an adjustable airsupply. The air emerges from the top plate 52 through the rows ofapertures a, b and c as jets of air.

The epoxy resin block 34 can be replaced with a block of sinteredmaterial or multi-layered mesh but there should be a complete sealbetween its edges and the walls of the chamber 30.

The air supported membrane 18 may have a pat terned surface. The patterncan take the form of recesses for applying localised heavy weight ofcoating since the weight of coating emerging from the head 2 is afunction of the force of pressure on the web 12 as supported by the belt18 against the coating head 2.

If desired a dual coating head may be provided for applying fast curingmaterials, i.e. short pot life two part adhesives and coatings byfeeding the components separately and mixing within the head.

The apparatus according to the invention can also be used for coatingwebs with for example foamed polyurethane by depositing the polymer andthe foaming agent together on the web so that it foams in situ aftercoating.

The apparatus can also be combined with a laminating nip for applying afurther layer of material to the web 12.

I claim:

1. Apparatus for applying coating material in a fluid state to a movingweb, which comprises:

a chamber for receiving the fluid coating material,

said chamber being defined by side walls and a substantially flat baseplate, the lower portion of said chamber being filled with a blockmember formed in place by pouring a hard setting material onto said baseplate, said base plate and said block material being drilledsimultaneously to provide therethrough a plurality of uniformlydistributed, perfectly aligned pores of uniform bore, said poresproviding direct fluid communication from said chamber to the movingweb;

means for dispensing coating material under pressure through said poresand onto the moving web; and

means for disposing the web in a flat condition against said base plate,said means comprising a moving belt bearing on the underside of themoving web and a plurality offluid jets acting on the underside of saidbelt.

2. Apparatus according to claim 1 wherein said block member is formed insaid chamber from a resinous material that is poured into said chamberand cured in Sltu.

3. Apparatus according to claim 1 wherein the said block is made ofmetal loaded epoxy resin.

4. Apparatus according to claim 3 wherein thediameter of the pores is ofthe order of 0.02 inch.

5. Apparatus according to claim 1, wherein said fluid jets comprise jetsof pressurized air, and wherein said jets are directed against theunderside ofsaid belt at locations corresponding to the nip points ofthe coating apparatus.

1. Apparatus for applying coating material in a fluid state to a movingweb, which comprises: a chamber for receiving the fluid coatingmaterial, said chamber being defined by side walls and a substantiallyflat base plate, the lower portion of said chamber being filLed with ablock member formed in place by pouring a hard setting material ontosaid base plate, said base plate and said block material being drilledsimultaneously to provide therethrough a plurality of uniformlydistributed, perfectly aligned pores of uniform bore, said poresproviding direct fluid communication from said chamber to the movingweb; means for dispensing coating material under pressure through saidpores and onto the moving web; and means for disposing the web in a flatcondition against said base plate, said means comprising a moving beltbearing on the underside of the moving web and a plurality of fluid jetsacting on the underside of said belt.
 2. Apparatus according to claim 1wherein said block member is formed in said chamber from a resinousmaterial that is poured into said chamber and cured in situ. 3.Apparatus according to claim 1 wherein the said block is made of metalloaded epoxy resin.
 4. Apparatus according to claim 3 wherein thediameter of the pores is of the order of 0.02 inch.
 5. Apparatusaccording to claim 1, wherein said fluid jets comprise jets ofpressurized air, and wherein said jets are directed against theunderside of said belt at locations corresponding to the nip points ofthe coating apparatus.